USACO 1.3.3

 1 /*
 2 ID:wconvey
 3 PROG:barn1
 4 LANG:C++
 5 
 6 */
 7 #include<iostream>
 8 #include<cstdio>
 9 #include<algorithm>
10 using namespace std;
11 struct mode
12 {
13     int a;
14     bool flag;
15 }arr[210];
16 struct node
17 {
18     int a;
19     int no;
20 }b[210];
21 int cmp1(mode x,mode y)
22 {
23     return x.a<y.a;
24 }
25 int cmp(node x,node y)
26 {
27     return x.a>y.a;
28 }
29 int main()
30 {
31     freopen("barn1.in","r",stdin);
32     freopen("barn1.out","w",stdout);
33     int m,s,c;
34     scanf("%d %d %d",&m,&s,&c);
35     for(int i=1;i<=c;i++)
36     {
37         scanf("%d",&arr[i].a);
38         arr[i].flag=false;
39     }
40     sort(arr+1,arr+1+c,cmp1);
41     for(int i=1;i<c;i++)
42     {
43         b[i].a=arr[i+1].a-arr[i].a;
44         b[i].no=i;
45     }
46     sort(b+1,b+1+c-1,cmp);
47     /*for(int i=1;i<c;i++)
48         printf("%d    %d***\n",b[i].a,b[i].no);*/
49     for(int i=1;i<m;i++)
50     {
51         arr[b[i].no].flag=true;
52         //printf("%d*******\n",b[i].no);
53         
54     }
55     int ans=0;
56     int start=arr[1].a,end;
57     for(int i=1;i<=c;i++)
58     {
59         if(arr[i].flag==true)
60         {
61             //printf("%d  *\n",i);
62             end=arr[i].a;
63             ans+=end-start+1;
64             start=arr[i+1].a;
65         }
66     }
67     ans+=arr[c].a-start+1;
68     printf("%d\n",ans);
69     //system("pause");
70     return 0;
71 
72